Modernize CMake and make minimal cpp version c++17

[stribor14]

• Use target_compile_features(cxx_std_17) instead of CMAKE_CXX_STANDARD
• Add target_link_libraries with Eigen3::Eigen
• Modernize target properties with multi-line format
• Add bezier::bezier alias for better CMake integration
• Set POSITION_INDEPENDENT_CODE ON
• Add -O3 -DNDEBUG optimization flags
• Fix include path to use CMAKE_CURRENT_SOURCE_DIR
• Remove __cpp_lib_make_unique polyfill (std::make_unique native in C++17)
• Remove __cpp_init_captures macro (lambda init captures native in C++17)
• Remove __cpp_structured_bindings macro (structured bindings native in C++17)
• Remove unused PolyLine class declaration
• Remove unnecessary #include from declarations.h"

Close #39